The present invention relates to a powered unit which may be joined to a vehicle having an engine pivotally mounted for movement into and out of engagement with a vehicle driving wheel and more particularly to an electric starter motor drive for the engine of a motorized cycle.
Motorized cycles, either bicycles or tricycles, are known wherein an engine is provided with a drive shaft on which is mounted a friction wheel or wheels for engaging a driving wheel of the cycle. Typically, these engines are started with a pull rope or by engagement with the drive wheel, which is then moved. It is desirable to have these motors started with an electric starter. Such an electric starter is especially advantageous where the operator of the vehicle is handicapped, such as a paraplegic.
One of the most serious problems of the paraplegic or other nonambulatory person confined to a wheelchair is that of mobility. Wheelchairs provide a limited mobility which is determined by the ability of the person to propel and control the wheelchair by hand. Powered wheelchairs, which are extremely expensive as well as being heavy and cumbersome, provide a greater degree of mobility, but are still limited in terms of their stability, and particularly in terms of the speed at which they are capable of traveling. Such units, moreover, are relatively complex, requiring substantial maintenance, and are relatively uneconomical in terms of cost and range of operation. Furthermore, there are many occasions on which powered wheelchairs are disadvantageous as compared with nonpowered chairs. For example, a paraplegic who is capable of driving a car may be required to hold his own wheelchair and place it inside the car when he enters the car and to follow a reverse procedure when he leaves the car. A powered wheelchair has proven to be too large and heavy in such situations.
Accordingly, it has been found to be advantageous to provide a unit which may be coupled to a conventional nonpowered wheelchair to convert the wheelchair into a powered vehicle and which may be uncoupled from the wheelchair to permit normal use of the wheelchair when desired. Such a powered unit is described in detail in a co-pending application entitled WHEELCHAIR-ATTACHABLE POWERED UNIT, filed Nov. 26, 1973, and issued as U.S. Pat. No. 3,912,032, on Oct. 14, 1975, of which the present applicant is a co-inventor. The unit described therein basically comprises a frame structure and a pivotable or steerable wheel rotatably mounted on a fork assembly which is in turn pivotably mounted within a cylindrical member forming a part of the frame structure. Handlebars are coupled to the fork assembly within the cylindrical member. An engine is pivotably mounted on the fork assembly and is pivotable between a position clear of the wheel and a driving position in which the engine drive shaft frictionally engages the wheels.
The frame assembly includes means for supporting the powered unit in an upright position when detached from a wheelchair and is readily couplable to the frame of a conventional wheelchair which has been appropriately modified to form a powered, three-wheeled vehicle.
One problem is using such a frictional drive arrangement in a powered wheelchair unit is in providing a simple and reliable mechanism for starting the engine. While it is possible to start the engine by engaging it with the driving wheel and then accelerating the vehicle to a low speed, this obviously could be done only with some difficulty by a handicapped driver. A rope or windup starter could be used to start the engine while it is disengaged from the driving wheel, but again these procedures may require more strength than the driver possesses. Furthermore, the engine cannot be started while its drive shaft is in engagement with the driving wheel unless the vehicle is moving and the starter motor must not be engaged with the engine shaft while the engine shaft is engaged with the wheel since this would ultimately burn out the starter motor.